Teenagers in England, Wales and Northern Ireland are waking up to their A-level results, with many hoping that their grades will be good enough to secure a coveted university place.

Experts have predicted that the pass rate will stall this year, amid fresh attempts by the exams regulator to tackle grade inflation.

It has been suggested that around 8% of exams will achieve an A* and just over one in four exams will score at least an A - the same as in 2011.

In a bid to tackle rising pass rates, Ofqual has told exam boards they will be asked to justify results that differ wildly from previous years. It means that the proportion of students awarded top grades is unlikely to increase greatly from 2011 levels.

Concerns have also been raised this year that changes to university admissions will mean that able teenagers who are predicted to score two As and a B, but just fall short, will struggle to gain a place.

Under a new system, there is now no limit on the numbers of students with two As and a B at A-level that universities can recruit, allowing them potentially to offer last-minute places to youngsters who do better than expected and meet this threshold.

But it means universities are likely to have less flexibility to admit students who just miss this standard, as there is still a strict cap on those who score less than AAB.

This year's students are already facing up to being the first to pay tuition fees of up to £9,000.

And Brian Lightman, general secretary of the Association of School and College Leaders (ASCL), said it would be a "tragedy" if bright teenagers who just missed their grades and lost out on a university place were disheartened. Mr Lightman said it was not yet known what effect the move would have, adding that there was a risk with any change that there will be "unforeseen circumstances".

Students predicted to score three As and get AAB could benefit, and despite missing their grades, still gain a place, he said.

Asked if there will be students who miss out on places, Mr Lightman said that happens every year. "When you are talking about those sorts of high grades, A and two Bs, people scoring those sorts of grades - for those to be disheartened would be a tragedy and we must do everything we can to enable them to get their place," he said.

"My advice to students would be don't give up, to look at the options that are open, and there are still plenty of opportunities out there."